How many dwarves are 500 dwarves?  I suspect it is more than it looks like.  Let's assume that, on an average, one soldier kills one opponent.  A really brave soldier kills five to ten opponents, and a real loser gets himself killed without killing anyone.  I don't know the real numbers, but I bet it is pretty close to that. 
Now let's think about the fighting prowess of dwarves.  In LOTR, Legolas and Gimili killed 41-42 orcs in a single night.  Let's discount orcs by 50%--it's half as hard to kill an orc as to kill a human.  So a dwarf is about equivalent to 20 humans.  500 dwarves is the equivalent to 10,000 human troops.  That's a formidable force.

Now also note that there just aren't all that many dwarves around, I bet there are no more than 20,000 total dwarves in the Northeast part of ME.  500/20,000=1/100 of the total population, percentage wise a substantial number.  Right now, the US population is 293,381,779 (5/31/2004), and the military is 1.4 million strong.  So there is one soldier per 209 people, about.  It looks like the dwarves may have sent their entire fighting force, based on this.  This suggests a most strong show of support for Thorin.

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